I was wondering what is the effect of sending continuos SIP registrations in the smartphones battery duration, to compare that solution (SIP register and proxy) with an Apple Push Notification alternative.

From my point of view, SIP registrations should be very expensive specially in NAT environments where typical SIP REGISTER expiration time is in the 30secs-2mins range to avoid expiration of mappings in the routers handling the NAT.

I did a quick test with a new iPhone 4 (without any background application) and the battery level at 100%.

The latest android version (2.3 Gingerbread) natively includes an implementation of a VoIP stack [1] [2]. It may or may not be included in the terminals depending on the manufacturer, but it is interesting to know the capabilities included and possible services to be deployed on top of them.

The android source code includes SIP and Voice support. Basically you can find two components wrapped by a high level call oriented API [3]Signalling: Managed library (Java) on top of standard NIST JAIN SIP stackVoice: Native library (JNI) including the implementation of:RTPCodecs: G711, GSM, AMR (all narrowband codecs)Echo suppression: according to the source code echo cancellation is too difficult to implement at this pointFixed size jitter buffer Device management for audio playing and recording
I'm not really sure if this kind of stack should be included in the OS or makes more sense to be included in each voice application deployed in the terminal (fostering innovation to increase the…